Description of Research
Research in Dr. Hoxie's lab is focused on identifying viral and cellular determinants that are relevant to the ability of HIV and SIV to infect cells and to evade host immune responses. Three specific areas of work include:

1. Producing modified HIV envelope glycoproteins for vaccine studies. This work is directed towards deriving HIV envelope glycoproteins that can elicit broadly neutralizing antibodies. Current approaches are deriving viruses lacking structures that are believed to shield the envelope from humoral immune responses.

2. Studies of CD4-independent isolates of HIV. Dr. Hoxie has described CD4-independent isolates of HIV-1 and HIV-2 that can infect cells using chemokine receptors without CD4. His lab has shown that the genetic basis for this phenotype results from mutations that expose the chemokine receptor binding site on gp120. Efforts are in progress to identify the structural basis for this effect and to use CD4-independent envelope glycoproteins as HIV vaccine candidates.

3. The role of the HIV/SIV cytoplasmic tail in pathogenesis. Dr. Hoxie's group has identified endocytosis signals in the cytoplasmic tails of HIV, SIV and FIV Env proteins that reduce Env expression on the surface of infected cells. Dr. Hoxie has proposed that these signals could be relevant in pathogenesis by enabling virus-producing cells to survive host anti-viral immune responses. He has shown in an SIV model that viruses with mutations in this domain are markedly attenuated in vivo and controllable by host immune responses. Ongoing studies are addressing the mechanism for this attenuation, the components of the host immune response that are involved, and defects in viral assembly that are believed to underlie this effect.

Rotation Projects
-Structure function studies of envelope glycoproteins focusing on mechanisms of CD4 and chemokine receptor engagement.
M-odulation of Envelope glycoproteins for the design of immunogens that can elicit broadly neutralizing antibodies.
-The role of the HIV/SIV cytoplasmic tail in pathogenesis.
-Studies evaluating mechanisms of neutralization sensitivity and resistance to antibodies.